A cardiac tissue ablation system according to one embodiment includes an elongate catheter configured to deliver a distal end thereof to a patients heart and an expandable member formed at the distal portion of the catheter. The expandable member has an elastic portion configured to conform to the shape of a target tissue region upon expansion. The system further includes an energy emitter movably disposed within a lumen of the catheter. The energy emitter is configured to deliver radiant ablative energy to the target tissue region. The system further includes a controller that includes a safety shut-off feature for automatically shutting off power to the energy emitter when a prescribed event occurs resulting in power to the energy emitter being stopped.
